This invention relates to diesel fuel engines, and more particularly, to devices that preheat diesel fuel for use in these engines.
It is well known that heating fuel prior to its introduction into the combustion chamber increases the efficiency of diesel engines There are many obstacles to overcome when designing a diesel fuel heating device. The object of these fuel heaters is to provide the combustion chamber with diesel fuel that is warmed to a predetermined temperature. The heat output of the fuel heater must be adjustable to satisfy the different amounts of fuel needed, depending on whether the truck is idling or accelerating. The fuel heater must also work within a wide range of environmental temperatures and pressures. The heat output required from the fuel heater at warm temperatures is much less than the heat output required when the outside temperature is below zero.
The fuel heaters must be inexpensive to manufacture and relatively easy to install. Savings from this type of device occur over an extended period of time due to increased fuel savings. Additionally, fuel heaters of this type decrease the amount of harmful emissions created by a diesel engine.
The prior art contains many attempts to overcome the problems faced when designing a gasoline fuel heater. In U.S. Pat. No. 4,146,002, issued to Quinn on Mar. 27, 1979, the gasoline is heated by passing it through helically shaped tubing that is surrounded by engine coolant. My prior invention, U.S. Pat. No. 4,367,717, issued Jan. 11, 1983, also utilizes engine coolant to heat the fuel. In this invention the fuel is passed through a heat exchanger which heats and regulates the fuel temperature as it passes into the automobile carburetor. Finally, my co-pending application, Ser. No. 121,672 filed on Nov. 17, 1987, now U.S. Pat. No. 4,846,137 also utilizes engine coolant to heat the gasoline prior to its introduction into the carburetor.
One attempt to overcome the many problems unique to diesel fuel heaters is disclosed in U.S. Pat. No. 4,700,047, issued to Crossett on Oct. 13, 1987. The Crosset patent discloses the use of an elongate heat exchange coil which is coiled inside a coolant containing housing. The use of a coiled heat exchange coil to transfer heat from the coolant to the fuel limits the ability of the fuel heater to heat the fuel in common winter temperatures unless the coolant is preheated or the heat exchange coil is lengthened.
The above described inventions illustrate some of the characteristics common to fuel heaters. The present invention addresses the need for a diesel fuel heater capable of overcoming the many problems unique to diesel fuel and the operating pressures of diesel engines. Therefore, due to the large number of diesel trucks present in our society and the limited fuel resources available, the need remains in the art for a diesel fuel heater which will improve combustion efficiency and decrease the amount of pollution created by these diesel engines.